[POS] Ecology and Enviromment

[POS-32] The relationship between network properties and ecological resilience in mutualistic systems

*Gohki Kasahara¹, Yutaka Osada¹, Michio Kondoh¹ (1. Tohoku univ (Japan))

Keywords:

community ecology,stability,network,mutualistic system

Recently, environmental changes such as global warming and anthropogenic disturbance have been occurring worldwide. It has been reported that in several natural ecosystems, the state of the ecosystem changes rapidly with gradual changes in the environment. This rapid change is called a regime shift. In recent years, ecological resilience has been actively studied to investigate the ability of an ecosystem to maintain its state without regime shift in response to environmental change. However, the relationship between system complexity (such as the number of species, interaction strength, and connectance) and dynamic stability has been studied for a long time, but the relationship between system complexity and ecological resilience has not yet been clarified analytically. In this study, we analytically derive the expected relationship between system complexity and ecological resilience using a random community approach for a mutualistic system. Specifically, we assumed a two-population symbiotic system with randomly-determined within-population competitions and inter-population mutualisms, and analytically determined the expected ecological resilience when perturbations reduce the mutual relationships. The results showed that increasing the number of species enhance the ecological resilience. The strength of the intra- and interspecific competition had negative effects on the resilience of the symbiotic system, indicating that the stronger the intra- and interspecific competition is, the stronger the mutualistic relationships are required for the survival of the system. Furthermore, we derived the ratio of the number of species in the two populations that maximizes the ecological resilience of the mutualistic system.